1. Field of the Invention
The present invention relates to a functional polymer with a supported pressure-sensitive luminophore that has high pressure sensitivity and rapid response, such as the one that can be used, for example, in sensors for the optical sensing of oxygen; and to a pressure-sensitive paint and pressure-sensitive element featuring the same.
2. Description of the Related Art
In conventional practice, pressure-sensitive paints known as oxygen sensors are coating materials obtained by dissolving light-excitable substances having oxygen quenching properties in polyvinyl chloride, polystyrene, and other oxygen-transmitting resins. Oxygen sensors are produced by applying such paints to matrices, but the extent to which the light-excitable substances and oxygen are brought into contact with each other in such sensors depends on the phenomenon of oxygen diffusion in the resins, and the sensors are thus disadvantageous in the sense that their oxygen sensitivity depends on the temperature and that the temporal response in relation to pressure variations is inadequate. In addition, the oxygen permeability of such resins decreases in low-temperature environments, making the sensors much less sensitive and unsuitable for use in measuring the ultralow-pressure on the surfaces of objects or detecting the traces of oxygen in the high-altitude environment; for use in measuring the distribution of pressure on the surface of a specimen in a cryogenic wind tunnel; or the like.
For this reason, the inventors have previously proposed a method in which a porous film is formed on the surface of a sensor matrix, and a light-excitable substance is directly adsorbed and retained on the porous film in order to bring the light-excitable substance into direct contact with oxygen rather than disperse this substance in the resin, and also proposed a sensor obtained using this method (Japanese Patent Application Laid-open No. H11-37944). Although the sensor produced by this method is an exceptionally good product in the sense that high oxygen detection sensitivity can be ensured and the reduction in sensitivity at low temperatures is minimal, problems still remain because there are limits as to the materials suitable for forming porous films as sensor matrices, it is impossible to say which specimens would be better for conducting operations in which light-excitable substances are adsorbed on the porous films, and the like.
The inventors also proposed a highly functional pressure-sensitive paint in which poly[1-(trimethylsilyl)-1-propyne] (referred to hereinbelow as xe2x80x9cpoly(TMSP)xe2x80x9d) is used as a binder for the light-excitable substance (Japanese Patent Application Laid-open No. 2000-249076). A paint obtained by using poly(TMSP) as the binder and admixing a light-excitable substance thereto is an exceptionally good, highly functional pressure-sensitive paint in which not only can high pressure sensitivity and low temperature sensitivity be combined and the oxygen sensitivity preserved even at the temperature of liquid nitrogen, but good response to pressure variations can also be obtained and spray coating made possible as a result of the fact that the binder has high oxygen permeability, and this high permeability is independent of the temperature and remains high even at low temperatures.
However, even these high-performance pressure-sensitive paints still have drawbacks that need to be overcome, such as nonuniform characteristics of the thin films formed by application, and a reduction in photoresponsivity due to luminophore aggregation during the evaporation of organic solvents.
An object of the present invention is to obtain a one-component pressure-sensitive paint in which the reduction in response due to luminophore aggregation can be prevented and a thin sensor film having uniform characteristics can be formed by retaining the luminophore in the polymer even after the organic solvent has evaporated and the thin film formed.
The functional polymer with a supported pressure-sensitive luminophore obtained in accordance with the present invention contains an acetylene derivative in which trimethylsilyl groups are bonded and in which a pressure-sensitive luminophore having oxygen quenching properties is also covalently bonded.
The pressure-sensitive luminophore containing a sensor portion that has oxygen pressure sensing functionality as oxygen quenching properties in the functional polymer with a supported pressure-sensitive luminophore in accordance with the present invention is present in a covalently bonded state in the acetylene derivative, so the luminophore molecules are retained as part of the acetylene derivative even when the organic solvent evaporates, and free aggregation is inhibited. It is thus possible to prevent response from being reduced by the aggregation of luminophore molecules during the evaporation of organic solvents, which is a drawback of forming films from conventional mixed-type pressure-sensitive paints.
Trimethyl-1-silyl propyne can be copolymerized with the acetylene derivative in this functional polymer with a supported pressure-sensitive luminophore. Trimethyl-1-silyl propyne is used as a material for preventing steric hindrance in polymer compounds containing this acetylene derivative.
The acetylene derivative in the functional polymer with a supported pressure-sensitive luminophore may be 5-(4-trimethylsilyl ethynyl phenyl)-10,15,20-triphenyl platinum porphyrin. The functional polymer obtained by copolymerizing this substance with trimethylsilyl-1-propyne is poly[trimethylsilyl-1-propyne-co-5-(4-trimethylsilyl ethynyl)phenyl-10,15,20-triphenyl platinum porphyrin].
The acetylene derivative in the functional polymer with a supported pressure-sensitive luminophore may be trimethylsilylethynylpyrene.
A pressure-sensitive paint can be obtained by admixing the aforementioned functional polymer with a supported pressure-sensitive luminophore into a solvent. Specifically, not only can production be facilitated, but high function reproducibility can also be achieved because the product can be applied and formed into a film using a solution that is merely dissolved in a solvent without the addition of binders or other materials. Storage and transport are simplified by allowing the product to stand as a pressure-sensitive paint, and the pressure-sensitive paint can also be used as needed in the form of a thin layer on a substrate by spraying the paint with a spray, applying the paint with a brush, or employing various other means.
Furthermore, a pressure-sensitive element can be obtained by applying and solidifying the aforementioned pressure-sensitive paint on a substrate. A highly uniform sensor film can be formed as a pressure-sensitive element on a suitable substrate when the aforementioned pressure-sensitive paint is thus applied. Forming such sensor films on the surface of a wing or other specimen and measuring the pressure distribution on the wing surface in a wind tunnel test or a test involving an actual device can be cited as an application example for these films.
The functional polymer with a supported pressure-sensitive luminophore newly synthesized in accordance with the present invention contains a covalently bonded pressure-sensitive luminophore and polymer, making it possible to prevent the luminophore from aggregating during the evaporation of the organic solvent, and to use the polymer in the formation of a uniform pressure sensor film that has high photoresponsivity. The functional polymer according to the present invention can be merely mixed with a solvent without any binders, stored and transported in the form of pressure-sensitive paint, and used at any time for application and film forming. This functional polymer has a single component as a pressure-sensitive paint, and is thus a paint that can be readily applied by spray coating, dipping, casting onto a substrate, or another method. It is also possible to use the pressure-sensitive paint as a film formed on a substrate by spraying or application, and to obtain a pressure sensor of uniform thickness. The distribution of pressure on a wing surface (specimen) can be measured with high sensitivity and resolution even in an ultralow-pressure environment by employing the pressure sensor thus obtained in cryogenic wind tunnel tests or impact wind tunnel tests.